The present invention relates generally to antennas, their manufacture and their mounting in timepieces. In particular, the invention relates to antennas capable of capturing an electromagnetic field bearing radio diffused messages and to timepieces including such antennas and a microreceiver for receiving messages captured by the antenna in order to transform such messages into data perceptible to the timepiece wearer.
Many timepieces exist which are equipped with an antenna and a microreceiver in order to capture radio diffused signals. If such a timepiece is in the form of a wristwatch, the antenna is generally located within the bracelet. However, locating the antenna in the bracelet of a watch gives rise to problems of providing connections between the microreceiver and the antenna which forms part of the bracelet, this latter being a movable element and generally hinged to the case by means of pins or lugs. The leadthrough of the antenna conductor gives rise to constructional problems with complicated means for connecting these two elements. At the leadthrough, for instance, the conductors are mechanically stressed and they are prone to break if means are not provided to avoid such breakage. These means are difficult to manufacture and complicate not only the assembly of the timepiece but also the changing of the bracelet, a bracelet moreover which must be specially built since it bears an antenna and which may not always be exchanged with a bracelet readily found on the market.
Attempts have been made to simplify the construction of such timepieces by housing both the antenna and the microreceiver within the case itself, thereby avoiding the mechanical stressing of the conductors which connect the antenna to the microreceiver. Swiss Patent No. 672 870, by the present applicant, describes in one embodiment a timepiece including an inductive antenna and a microreceiver entirely confined within the space bounded by the case. The longitudinal axis of the coil windings forming the antenna is arranged parallel to the longitudinal direction of the bracelet. In this embodiment, the windings each comprise two interconnected sections, one of which is formed by a metallisation layer deposited under the glass and the other of which is formed by a metallic wire sunk into the back cover of the case.
Swiss Patent No. 679 356, also by the present applicant, describes an alternative construction of this timepiece, in which the coil windings are wound around a second glass and an internal casing provided in the case. Grooves are provided in the second glass and in the internal casing to facilitate the placement of the windings. The connection between the RF module of the microreceiver and the antenna is effected by bringing the coil windings directly into contact the RF module and thereafter soldering them in place.